In an electrophotographic image forming apparatus which forms a copied image by transferring a toner latent image formed on a transfer medium onto printing media such as plain paper sheets stored in a paper feed unit, and thermally fixes the transferred toner latent image, it is important to manage image information having undergone copied image formation, in order to browse and reuse the information concerning the copied image. When image information of a copy source is digital data, various pieces of attached information such as the importance, author/owner, formation date, and keyword of the image information can be collectively managed together with the image information by, for example, forming a database from the image information. This method allows easy retrieval and update of the image information, and hence is effective to browse and reuse the information (for example, Japanese Patent Laid-Open No. 59-036867).
On the other hand, management which relates information to an object by using an RFID (Radio Frequency Identification) tag (to be referred to as a “radio identification tag” hereinafter) is also attracting attention. For example, Japanese Patent Laid-Open No. 2002-337426 is a technique which applies a printing medium to a copying machine or printer by attaching a radio identification tag to the medium.
Unfortunately, if the original data is not digital data but image information printed on a sheet-like paper medium (to be referred to as a “paper sheet” hereinafter), or if image information is obtained by printing digital data on a printing medium by an image forming apparatus, no attached information as described above can be related to the image information any longer. Therefore, these pieces of information cannot be collectively managed by a digital information database. This makes it very difficult to browse or reuse information concerning printed image information.
For example, when image information is once printed on a printing medium on the basis of digital data, the original digital data cannot be retrieved from the medium unless information for retrieving the digital data is present. Accordingly, to reuse the printed image information as digital data, this image information printed on the medium must be digitized again. Furthermore, if the original digital data is changed or modified by editing later, the result of editing cannot be reflected on the image information printed before editing. In this case, therefore, the printed image information must be digitized again and edited again. This imposes a repetitive operation burden on an operator.
Also, even when a radio identification tag is used, a read/write tag by which data can be read out from and written in a memory is still expensive compared to a read-only tag (u chip) by which it is only possible to read out data stored in a memory in advance. Additionally, using a radio identification tag by attaching it to a printing medium beforehand poses many problems in respect of the reliability.
For example, when a printing medium is passed through a fixing device in an image forming apparatus which forms an image by transferring a toner image onto the printing medium, a radio identification tag is placed in a high-temperature environment together with the printing medium. Consequently, a device forming the radio identification tag may be physically destroyed, or may cause dielectric breakdown by a high electric field applied during, for example, transfer inside the image forming apparatus and may become unable to operate. That is, image formation with a radio identification tag attached to a printing medium beforehand is difficult in respect of the reliability of the radio identification tag. Also, generally no printing media having radio identification tags attached to them have spread yet, so it is presently difficult to specially order and prepare such printing media in advance.
Accordingly, it is important to use a printing medium normally put on the market, and attach a radio identification tag to this printing medium so that the reliability of the radio identification tag can be maintained.